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93 3.0L fuel injection problem


dangilroy

New Member
Joined
Jul 28, 2008
Messages
3
Vehicle Year
1993
Transmission
Manual
I've got a problem with my 93 Ranger 3.0L V6. I think it's a fuel injection problem.

The truck starts and runs normally for a couple minutes, or about a mile. Then it loses power and will barely idle, and has little or no throttle response above idle. It first it did this erratically, and returned to normal, but for the last few weeks, it's doing it all the time

I changed the fuel filter, and the fuel pressure is normal.

It seems like it loses power around the time it should be switching from open loop to closed loop.

I can take the electrical connector to the MAF off and it runs ok. It might be a little rough, but it has good power. That's how I've been running it the last few weeks. I'm guessing that disabling the MAF, puts the system into open loop and gives me a rich mixture, but I have no way of really knowing.

With the MAF disconnected I get codes 158, 157, 159, which mean MAF out of range, or voltage too low, or too high.

With the MAF connected and the engine idling rough, I get codes 136 and 172 = #1 and #2 banks running lean. But no codes pointing to specific hardware.

Are there any fuel injection gurus out there who can help me make sense of this? I'd rather not just start changing parts at random.
 
Perhaps the MAF is has gotten dirty. the unit used a heated wire to measure the air flow into the engine. If the wire is dirty it will read the air flow improperly, most likely less CFM than the actual airflow. This may account for your engine running poorly. If it thinks there is a low RPM/low air flow condition, it will inject less fuel causing reduce engine output.

Check out this link to our tech forum.......
it is for the 4.0L but the procedure for cleaning would be similar.


hope this helps.....

Rob
 
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These symptoms lead me to think you have a vaccuum leak.

Unmetered air is entering the engine after the MAF.

Examine your PCV tubing and elbows for cracks. Follow all your vaccuum lines and inspect them for cracks, burns, etc. Don't forget the brake booster and HVAC lines. Should be a vaccuum routing decal under the hood.

You might also look at the EGR system, if it has one. Remove the vaccum line from the EGR valve and plug the line. See if it improves (ignore the CEL and codes that'll generate). Might also hand cycle the EGR valve with it disconnected; maybe it isn't seating fully closed.
 
dangilroy - at what RPM and throttle position are u experiencing this trouble?
 
Thanks for all the leads, I will check them out.

I already checked the MAF and I don't think it's the problem.

But I haven't checked the oxygen sensors, and I didn't yet do a thorough seach for vacuum leaks.

Once the problem kicks in, after about 2 min of warmup, the engine has a very very rough idle, and has either zero throttle response (won't run above idle), or an erratic throttle response that comes and goes.
 
just_Randy and Earl have a good point, the vacuum leaks can cause the MAF to show funky readings. I doubt the o2 sensor will cuase such idle problems, unless it is cycling, (which is unlikely given the environment it is in). A large exhaust leak would be necessary for cycling.


An afterthought...... what about the temp sensor/???intake air charge sensor??? when cold it runs ok, when quasi-warm it runs bad


rob
 

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